Bi2O3-Bi2WO6 直接Z-scheme异质结的制备、表征及光催化还原U(VI)的性能

Preparation and characterization of Bi2O3-Bi2WO6 direct Z-scheme heterojunction and photocatalytic reduction of U(VI) under visible light irradiation

  • 摘要: 根据能带理论,以Bi(NO3)3·5H2O为铋源,采用水热煅烧法制备了Bi2O3-Bi2WO6复合光催化材料,SEM、XRD、XPS、紫外可见漫反射(UV-vis DRS)、电化学阻抗(EIS)等表征手段对材料进行表征与分析,以U(VI)为目标污染物,在可见光下进行光催化还原U(VI)的性能研究。结果表明:与纯Bi2WO6相比,Bi2O3-Bi2WO6复合材料具有较高的光催化活性,当Bi2O3与Bi2WO6的摩尔比为2.4∶1时,Bi2O3-Bi2WO6的光催化活性最好,光催化活性增强归因于Bi2O3的加入,在Bi2O3与Bi2WO6界面形成的直接Z-scheme异质结,提高了光生电子-空穴的传输速率,降低了其复合率;另一方面,Bi2O3的加入使Bi2WO6带隙变小,扩大对可见光的响应范围,从而提高了Bi2O3-Bi2WO6光催化剂的活性。本研究为设计和合成具有高可见光活性的光催化剂和了解增强U(VI)光催化还原机理提供了新的思路。

     

    Abstract: According to the energy band theory, Bi(NO3)3·5H2O was used as bismuth source to synthesize Bi2O3-Bi2WO6 composite photocatalyst materials by hydrothermal calcination. The samples were characterized by means of SEM, XRD, XPS, DRS and EIS, respectively, and the photocatalytic activity was assessed in terms of reduction of U(VI) under visible light irradiation. The results show that the prepared Bi2O3-Bi2WO6 composite materials exhibit enhanced photocatalytic performance for the photo-reduction of U(VI) than the pure Bi2WO6, the optimized photocatalytic efficiency for U(VI) is achieved when the mole ratios of Bi2O3 to Bi2WO6 is 2.4∶1. The improved photocatalytic activity is ascribed to the direct Z-scheme heterojunction between Bi2O3 and Bi2WO6, resulting in the rapid interfacial transfer of photoelectron-hole and wide light response range. This work provides a new idea to design and synthesize the photocatalysts with high visible light activity and understand the enhanced photocatalytic reduction mechanism of U(VI).

     

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